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Plant Science & Conservation

Conserving plants is one of the most significant challenges of our time—and a major focus at the Chicago Botanic Garden. From studying soil to banking seeds, from restoring habitats and protecting endangered plant species to developing new ones, Garden scientists are fighting plant extinction, pollution, and climate change through diverse and exciting research.

Do they have a “type,” or it is just economics?

Fast and graceful, hummingbirds flit from flower to flower—but which ones and why? A Chicago Botanic Garden scientist and his collaborators recently made some unexpected findings on the subject.

It’s a common perception that plants are perfectly matched to their pollinators and that each pollinator has a specific flower type that they are attracted to. For hummingbirds, many gardeners and scientists alike have long assumed their flower type to be one that is strikingly red, tubular, and scentless.

Flowers that are often thought of as typical choices for hummingbirds:

Wyoming paintbrushCastilleja linariifolia

Giant red paintbrushCastilleja miniata

Scarlet giliaIpomopsis aggregata

It’s not hard to see why anyone might assume that hummingbirds and certain kinds of flowers are perfect matches. Hummingbird visits to flowers are visually striking, and many casual observations suggest a typical and consistent set of floral characteristics associated with this plant-pollinator interaction. The vibrant red or orange color of blooms appear as if they were designed specifically to attract the eye of hummingbirds. A hummingbird’s long bill appears perfectly matched for the extraction of nectar from the long, tubular flowers. But don’t be fooled—while it’s satisfying to organize flowers and pollinators and their interactions into clear-cut categories (known as pollination syndromes), these human constructs may mask what is really going on in nature.

Many “typical” hummingbird flowers belong to species that produce diluted nectar with lower sugar concentrations. Yet the hummingbird’s signature hovering flight burns massive amounts of calories. From the hummingbird’s perspective, it would therefore be much more efficient to drink from flowers with more concentrated nectars. Hummingbirds are also known to have acute color vision and show no innate preference for the color red—in other words, there is no reason for them to exclusively focus on red or orange flowers. And their long and slender bills are perfectly capable of extracting nectar from both long and shallow flowers. Finally, hummingbirds do have a sense of smell. So why would hummingbirds go out of their way to visit a limited selection of reddish, long-tubed, scentless flowers that produce cheaper nectar when they could feed from more suitable nearby sources in a diverse buffet of flowers?

Flowers that are “atypical,” or lacking the characteristics we associate with hummingbird-visited flowers (note that they vary in color, shape, odor, and nectar concentration):

Nuttall’s larkspurDelphinium nuttallianum

Glacier lilyErythronium grandiflorum

Ballhead waterleafHydrophyllum capitatum

The Garden’s Paul CaraDonna, Ph.D., and his research collaborators Nickolas Waser, Ph.D., and Mary Price, Ph.D., of the Rocky Mountain Biological Laboratory, discovered that it all comes down to the basic economics that maximize energetic gain at minimal energetic cost. While camping and conducting research across the American Southwest, the three researchers kept observing something curious and unexpected: hummingbirds routinely visited flowers that lacked the expected typical characteristics of hummingbird flowers.

To make sense of these observations, the team dug back into their field notes from the past four decades and began to look more closely at the potential profitability of atypical vs. typical flowers for hummingbirds. Their field notes contained information on hummingbirds’ foraging rates at flowers and measurements of the nectar sugar concentrations; with this information, the team was able to calculate the energetic profits that could be gained by a hummingbird foraging at either type of flower.

What the team found was that typical and atypical flowers overlapped considerably in their energy content and profitability for hummingbirds. In other words, most typical flowers were no better than most atypical flowers and most atypical ones were no worse than most typical ones. Taken together, this research reveals that hummingbirds are making an energetic profit—not a mistake—when visiting these atypical flowers. In fact, atypical flowers may play a critical yet underappreciated role in supporting hummingbird migration, nesting, and populations in areas that seem to be lacking in suitable floral resources. The results of this research were recently published in the peer-reviewed scientific journal The American Naturalist. Neither typical nor atypical flowers are categorically better or worse than the other, and instead show considerable overlap in the energetic gain they offer to foraging hummingbirds.

Many hummingbird conservation efforts focus solely on typical flowers. Perhaps you have come across suggested hummingbird plant lists that are dominated by typical species. Now knowing that atypical plants can support the migration and residence of hummingbirds, we can consider more than just the typical plants as food resources in habitats and along migration routes.

Guest blogger Karen Wang graduated with a B.S in ecology and evolutionary biology and a B.A in creative writing from the University of Arizona in 2017. She has worked as a research assistant on a variety of projects, mostly involving pollinators such as bees and moths.

Have you ever noticed the first crocuses poking out of the snow or the brilliant, changing colors of fall leaves? If so, we need your help with the critical work of studying how plants are affected by a changing climate.

Budburst, a project adopted by the Chicago Botanic Garden in 2017, brings together citizens, research scientists, educators, and horticulturists to study “phenology,” or the life-cycle events of plants. Wildflower phenology events, for example, are fairly simple: first flower, full flower, first fruit, and full fruiting. Deciduous trees, on the other hand, are more complex, with stages from first buds to leaf drop.

Sweetgum (Liquidambar styraciflua) seed in the summer.

Sweetgum (Liquidambar styraciflua) leaves in the fall.

Budburst builds on the basic human drive to notice this kind of changing nature around us and record the information to a database for scientists to review. As director of Budburst, I’m excited to hear about your observations on Fall into Phenology, a study on the autumnal changes you see in plants, or the Nativars Research Project, which looks at how bees, butterflies, and other pollinators react to cultivated varieties of native plants.

Budburst’s Fall into Phenology is not limited to just leaf color and seed; it is about observing plants in the fall. This will be my second autumn with Budburst and the Garden, and I’m looking forward to watching some my favorite plants go through their life-cycle changes. I’ll be keeping an eye on the sweetgum trees (Liquidambar styraciflua) underneath my window at the Regenstein Learning Campus, for instance. I can’t wait to see the beautiful shades of yellow or orange or…well, you just never know.

The plants you see from your train seat on the Metra Union Pacific North line may help conservation scientists learn about how urban areas impact native bees.

Although most people think of honeybees when they think about bees, there are more than 4,000 native bee species in the United States and 500 species in Illinois alone. Like their honeybee counterparts, native bees are undergoing global declines, making them an important conservation concern. With the growth of urban areas, native bees may be faced with new challenges, yet we don’t know the extent that urban areas impact native bees.

My research at the Chicago Botanic Garden is investigating how urban areas may affect native bees in Chicago. Chicago is an ideal city to study the impact of urbanization on native bees because the intensity of urbanization slowly wanes from the urban core of the city out into the surrounding suburbs.

My research is focused on native bee species in Illinois like these Megachilid(leaf cutter) bees.

Part of that research is about bringing public awareness to the other native bees we have around Chicago.

To explore native bee communities along this urbanization gradient, I have a series of eight sites along Chicago’s Union Pacific North Metra (UP-N) railway. I chose the sites along the rail line because they followed a perfect gradient from very urban to very suburban. I was also drawn to them because most of the vegetation around the sites is unmanaged and composed of similar species.

All of the sites vary in the levels of green space and impervious surface (concrete/buildings) surrounding the sites. Sites near downtown are surrounded by nearly 70 percent impervious surface, while sites near the Chicago Botanic Garden are surrounded by just 15 percent impervious surface.

Studying bees in this area along the Metra line allows us to ask a variety of questions about native bees. For instance: Are there fewer bees in highly urban areas? Are there different bees in natural areas compared to urban areas? Do the bees in highly urban areas have different traits than those in natural areas?

Andrea and an intern collect bees along the Metra line.

This summer, a few interns at the Garden and I have been gathering and sampling bees at each of my eight field sites. To catch the bees, we use two methods. First, we set out fluorescent colored bowls with soapy water that attract and capture the bees. Secondly, we use a butterfly net to capture bees at the site throughout the day. When we are finished sampling, the bees are taken back to the lab at the Garden’s Daniel F. and Ada L. Rice Plant Conservation Science Center and pinned for future study.

In addition to collecting the bees, we also record all of the flowering plants and count how many flowers are blooming at the sites.

Although our days are currently filled with fieldwork and pinning, in the fall we will spend almost all of our time in the lab identifying the bees down to the genus or species level. When we have all of the bees identified, we can then start analyzing the data for my master’s thesis and answer some of the questions we have put forth. We suspect we will see a higher abundance and diversity of bees in sites located in more natural areas with more flowering plants.

My research will help us understand how urban areas are shaping native bee communities and help us determine what landscape features promote native bee diversity in urban environments, some of which can be implemented in urban restoration projects. We also hope that this work will illuminate the amazing diversity of native bees we have here in Chicago.

As plant collectors, we spend a lot of time and energy researching the flora of the areas we are going to visit. We search out areas of the world where the climate is similar to that of the midwestern United States, and we make lists. Lots of lists.

Massive spreadsheets document travel plans, emergency contacts; high-value germplasm that we hope to find at each of our planned collection locations; and costs: airfare, gasoline in the country, driver wages, botanist guides, food, and lodging. All of this data is condensed into a one-page document that our hosts submit to the national environmental agencies within each country for approval and permits for the trip. Among our goals on plant-collecting trips is to collect seeds to conserve and to look for plants of horticultural interest to display in our collections.

Paeonia tenuifolia

Invariably, some of the treasures we return with are unanticipated. Such was our discovery of a very large population of Paeonia tenuifolia that was unknown to Georgian scientists in the remote and sparsely populated Vashlovani Reserve—a peninsula-shaped area surrounded by Azerbaijan on three sides, containing large rolling hills breaking into badlands—areas so heavily eroded I thought I was in the Badlands of the Dakotas.

We were in search of seeds of unusual bulbs in the Vashlovani Nature Reserve with Peter Zale from Longwood Gardens (the trip organizer), Panyoti Kelaidis from the Denver Botanic Gardens, and Manana Khutsishvili from the Institute of Botany, Ilia State University.

It was one of those breathtakingly beautiful days, with the rolling grasslands backdropped by the snow-covered peaks of the Greater Caucasus Mountain Range. Dirt roads had not been graded in quite a while, and the sun-baked ruts left over from the winter rains gave rise to the trip joke: shaken, not stirred. This was definitely four-wheel-drive country.

One of our target species in this area was Merendera trigyna, a beautiful spring-flowering Colchicum relative with pale pink to white flowers about twice the size of Crocus and blooming about the same time. Our data source was a herbarium voucher on file with the Institute of Botany Herbarium in Tbilisi. Peter had entered the coordinates into the GPS receiver after lunch, and the road seemed to head in the correct direction. A couple of hours later we were on the border with Azerbaijan and the coordinates suggested we needed to cross the border—not a match with the written description of the location on the herbarium voucher.

We continued to skirt the border, and an hour later we found a hilltop that allowed Manana to make a cellphone call back to the herbarium in Tbilisi. Thirty minutes further down the track, on another exceptionally high hill, we learned the coordinate system recorded on the voucher was from a Russian GPS system, not the American system our GPS was programmed for.

By that time it was too late to retrace our steps. In new territory for all of us, we continued on the track paralleling the Azerbaijan border, knowing that eventually it would lead us to a small Georgian town. By this time, it was about 6 p.m., and as we surmounted another rise we were greeted with thousands of fernleaf peony (Paeonia tenuifolia) in full flower. Each flower was the size of a salad plate, and a deep, intense red. Unlike the 8-inch-high representatives of this species in our American collections, the whole population was 2.5 to 3 feet in height, with an equal width. This population was unknown to the Georgian scientific community until we managed to get lost and found it in the process of working our way back home.

Paeonia tenuifolia in the remote and sparsely populated Vashlovani Reserve; the Caucasus Mountains in the background.

A trip is planned for 2019 for the Republic of Georgia. It is timed to collect seeds from this population, as well as the nine other species of peonies native to this floristically rich country. Who knows what unsuspected treasures we will discover next year?

Hosted by: Jeremie Fant, Garden scientist and plant genetics guru

How do you bring an endangered plant species back from the brink of extinction? The answer might be found in zoo animals.

That’s the inspiration for Chicago Botanic Garden scientist Jeremie Fant’s latest research. Fant, a molecular ecologist and plant genetics guru, is working with other botanic gardens around the world to develop conservation and reintroduction plans modeled after the ones used by zoos to protect endangered animal species.

“When we conserve plant species, it’s possible to preserve hundreds of individuals, and the genetic information they contain, by banking their seed or using cuttings to propagate them,” said Fant. “But when this is not possible, these plant collections are maintained by continually crossing with other plants to produce new seed. This is akin to animals in zoo collections. Zoos have used genetic information to develop ‘studbooks’ to decide what crosses are compatible so they maintain genetic diversity and prevent inbreeding.”

Fant’s work is based on zoological cases including black-footed ferrets in the 1980s. Zoologists created a breeding program that ultimately reintroduced the threatened species back into the wild. The zoologists used genetic information taken from the remaining black-footed ferrets, and bred a strong, biodiverse population that could keep the animals healthy and, more importantly, increase numbers, which is the aim of all good conservation programs.

Fant’s work centers on one plant in particular: the Brighamia insignis, or “Cabbage on a stick,” or as we’ve fondly named it, “Cabby.” This is Cabby’s story:

To stay tuned on what Fant, and the rest of the Garden’s conservation scientists are doing, check out the latest news at chicagobotanic.org/research.